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How I Switch TV
Written March 3, 2005


For any of you who may be interested, I feel obligated to report that my home TV setup has gotten even more complex with the recent addition of a DVD recorder.

Most of my video sources are available as inputs to my main high-definition TV, which can display:

• analog cable channels using its twin RF tuners
• video from a VHS tape machine called "P"
• S-Video from the new DVD recorder
• progressive-scan video from a DVD player
• high-def or standard video from a cable box
• high-def video from an off-air digital tuner

There are also three small TV sets that can show the outputs of the "P" VHS machine; the DVD recorder; and either the cable box or the "M" VHS machine (by choosing channel 3 or channel 4).

For recording purposes, the DVD recorder receives digital cable channels from the cable box via an S-Video connection.  It can also use its RF tuner to record any of the analog cable channels; the same goes for the two VHS tape recorders.

All these functions require a lot of wiring, and you'd think that it would be enough.  But it's not.  There are other connection combinations that I occasionally find useful.  To handle these, I hit upon the idea of putting together a little four-by-four routing switcher, using a pair of mechanical switching boxes I bought at the local K-Mart.

Each of these boxes is designed to choose among four inputs and send the choice to one output.  Each “input” and “output” consists of a set of three cables in my case:  composite video (yellow) and stereo audio (white and red).  Although the boxes also can switch S-Video, I'm not using that format here because not all of the connected devices can handle it.

The box on the left is my Source Selector, as described above.

I've hooked up the other box backwards, so it can be the Destination Selector.  In other words, the output from the Source Selector is connected to the Destination Selector's “output,” which actually functions as an input.  Each of the Destination Selector's four “inputs” functions as a part-time output, feeding a different device.

Thus if I punch the button to choose Source 3 (the cable box), I send that signal to the Destination Selector.  Then if I punch the button to choose Destination 3 (the VHS machine called “M”), that machine can record what's on the cable box.

For another combination, I can choose Source 2 (the high-def TV's NTSC output).  Whatever that main TV set is displaying is thereby fed to the Destination Selector, where I can choose Destination 4 to send it to the remote TVs.  These are three more small TV sets around my apartment, plus a stereo audio receiver.

Other combinations:

1 to 1 allows me to dub a VHS tape to DVD.

3 to 2, or 3 to 3, allows me to record a digital cable channel on VHS.

3 to 4 allows me to choose one of my cable system's all-music channels and send it to the audio receiver so I can listen to the music without turning on any of the TV sets.

And so on.

The only manual “patching” that's still required involves an unusual situation:  when I want to record an FM radio program onto VHS.  For that, I can unplug the white and red cords from Source 3 and replace them with another pair that's dangling nearby.  This pair comes from the audio receiver, which I've tuned to the desired radio station.

Or I could replace only the white cord and leave the red one in place.  That way I could videotape a Steelers game with the TV announcers on the right channel and the local radio announcers on the left!



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